Samples of sewage, sewage sludge and sewage effluent from one or more of four sewage treatment plants were examined for the presence of Leptospira, Mycobacterium, Escherichia coli, Brucella abortus and Bacillus anthracis. Brucella abortus and Bacillus anthracis were not isolated. Eleven strains of E. coli potentially enteropathogenic for calves or piglets, eight pathogenic strains of Mycobacterium and one pathogenic Leptospira strain were isolated from 101, 189 and 189 samples respectively.

Sewage sludge is not considered to play a major part in the epidemiology of disease caused by these organisms.

Baiting with 0·005% bromadiolone in medium oatmeal or soaked wheat completely controlled infestations of warfarin-resistant rats on farms when surplus amounts of the poisoned baits were maintained until rats ceased to feed on them. The speed with which control was achieved was the same as with other anticoagulants that have been tested in this way.

Poison baiting with 0·005% bromadiolone for only 1, 4 or 7 days achieved respectively about 49, 77 and 81% control of similar farm rat infestations.

Modified brilliant green agar (BGA), Muller-Kauffmann tetrathionate, Rappaport's and selenite F broths were compared for their efficiency in isolating salmonellas from pigs and their excreta. It was concluded that BGA and Rappaport's broth were the media of choice. Where searches were made for Salmonella choleraesuis alone, the use of a trehalose McConkey agar provided a rapid method of differentiating S. cholerae-suis, which does not ferment trehalose, from the majority of other salmonellas, which do ferment trehalose.

Casualties were collected from two farms where infection with S. cholerae-suis was endemic. The isolation rates of S. cholerae-suis from different carcase sites were compared in order to determine the relative importance of the salivary, upper respiratory and faecal routes of excretion. S. cholerae-suis was isolated from numerous carcase sites in carriers including the salivary glands, tonsils, trachea and lungs. However, isolations from the nasal passages, mouth, pharynx and gastro-intestinal tract of carriers were either infrequent or absent. When, in a further study, S. cholerae-suis was isolated from only 3/414 faeces, 1/170 nasal swabs and not at all from 170 oral swabs taken from live pigs, it was concluded that there must be more significant modes of transmission than from the salivary glands, upper respiratory or gastro-intestinal tracts. Cannibalism was considered to be a possibility.

In contrast to S. cholerae-suis, other salmonellas were frequently isolated from randomly collected faeces and from the gastro-intestinal tract as well as other sites in casualties.